Various viscous fluid clutches have heretofore been provided; however, because of certain design characteristics they are beset with one or more of the following shortcomings: (a) the clutch is of complex costly construction; (b) the clutch is susceptible to an inordinate amount of servicing and maintenance; and (c) the relative rotational speed of various drive members embodied in the clutch cannot be readily modulated in response to various ambient temperature changes.